Projectile firing control system



Aug. 21, 1956 J. J. JAKOSKY PROJECTILE FIRING CONTROL SYSTEM 2 Sheets-Sheet 1 Filed July 31, 1952 INVENTOR.

Aug. 21, 1956 Filed July 51, 1952 J. J. JAKOSKY PROJECTILE FIRING CONTROL SYSTEM 'lllllli v 'll,,IIIIII'IIII'IIIIIIII A! j 2 Sheets-Sheet 2 INVENTOR JOHN J. JAKOSKY BY M M ATTORNEYS rnorncriLn no coNrRoL SYSTEM John .I. .lakosky, Los Angelles, Calif assignor, by direct and mesne assignments, of forty per cent to International Geophysics, Inc, Los Angeles, Calif, a corporation of California, and sixty per cent to Signal Oil and Gas Company, a corporation Application July 31, 1952, Eerial No. 301,941

6 Claims. (Cl. 89-1) This invention has to do with apparatus for remotely controlling the explosion of a projectile so as to cause detonation at an exact, predetermined distance or height above the ground.

My invention finds its chief utility in the field of determining the location and characteristics of subterranean strata by reflecting from the strata seismic waves created by an explosion in the air above the ground. In such work it becomes essential, in order to obtain maximum seismic signal/interference ratio at the detecting and recording equiment, and in order to keep to a minimum interfering sound waves and ground roll, to maintain some control of the frequency bands of the major energy components of the explosion. The only presently known way of accomplishing control of the height of the explosion is by utilizing time-delay detonators. However, it has been found that time-delay detonators will not provide critical control of the height of explosion. This is due chiefly to the following factors: (1) time-delay detonators have inherent inaccuracies varying from 10 to 25 percent of their rated values, and (2) variations in the velocity of the projectile as it leaves the mortar, those variations running from to 50 per cent of their theoretical values. It is easy to understand, therefore, that if it be critical that a projectile be exploded at a precise height above the ground, such unknown and uncertain elements are apt to result in great variation from the desired shot point.

It is an object of my present invention to provide apparatus by which accurate control of the height of detonation of a projectile or projectiles may be obtained.

It is a further object to provide apparatus by virtue of which, when the projectile reaches a predetermined height, its momentum functions automatically to cause detonation of its explosive charge.

Another object is to provide novel means for winding the firing cable into a spiral coil, for retaining it in such coiled position and for facilitating feeding out the cable during upward travel of the projectile to which one end of the cable is attached.

Other objects and advantages will appear hereinafter.

Without intending thereby to limit the broader scope of the invention, except as may appear from the appended claims, I shall now describe preferred adaptations of my invention, for which purpose I shall refer to the accompanying drawings wherein:

Fig. l is a schematic perspective of the apparatus;

Fig. 2 is a wiring diagram;

Fig. 3 is a medial sectional view of a projectile;

Fig. 4 is a plan view showing a modified arrangement of leads;

Fig. 5 is a top plan view of a modified form of means for spirally winding the projectile firing leads;

Fig. 6 is a perspective showing the parts of the device of Fig. 5 separated;

Fig. 7 is an enlarged fragmentary section taken on line 7-7 of Fig. 5; and

2,759,397 Patented Aug. 21, 1956 Fig. 8 is an enlarged fragmentary section taken on line 88 of Fig. 6.

Referring now to the drawings, I show a projectile P in course of being mounted in a conventional mortar M to be propelled upward by virtue of detonating the propellant charge 5 in the projectile, which is accomplished by closing an electrical circuit, through plug 8, to the firing squib 6 in the projectile through leads 7. If desired, the projectile casing may be closed at its bottom end and the propellant charge may be placed separately in the mortar below the bottom end of the projectile. The explosive charge 10 in the projectile is exploded at the desired height by closing an electrical circuit to a detonating cap 15 through leads 20, as will be described.

As shown in Figs. 1 and 2, the firing box 25 carries an electrical source, such as batteries, not shown, from which circuit wires 26 extend. A pair of switches 29, 29a control the circuit for firing the squib 6 of the projectile P. Those switches constitute a two-hand firing control, the switches being actuated by a pair of push buttons 23, 24, one in each end of the handle provided for the firing cable 28. Of course other suitable means may be provided for closing the circuit to the squib, aithough I find the above-described arrangement to be preferable because of its safety features.

The leads 20, controlling the firing of the explosive charge it) in the projectile, are connected into the circuit as shown in Fig. 2 and adjacent one end of the leads they are physically connected to a trip lever 30 which actuates a switch 31 to close the circuit to the detonating cap 15.

Leads 20 are pro-selected to be of a length equal to the height above the ground at which it is desired to detonate the explosive charge It and preferably are arranged in accordion folds so that they will not become tangled as the projectile moves upwardly. Of course, instead of the accordion folds, other arrangements of the leads 20 may be provided, such as a spiral arrangement, as shown in Fig. 4. Those leads preferably extend through the top of the projectile casing 28 and are securely fastened to the top, to prevent disengagement when the projectile is ejected upward.

In operation, after the leads 20 are selected of the desired length and connected into the projectile and into the circuit in the manner described, the operator presses the push buttons 23, 24, thus closing the switches 29, 29a and closing the circuit to the squib 6, which explodes the propellant charge 5, causing the projectile to be projected upwardly. Upon reaching the desired height, the length of the leads 20 will become spent and the momentum of the projectile will cause them to trip the lever 30, actuating switch 31 and closing the circuit to the detonating cap 15.

To prevent accidental firing of the projectile while it in the mortar, I show a safety switch in Fig. 1. Here a plunger 4% is slidably mounted in a hole in the side of the mortar, the plunger being urged outwardly by a leaf spring 41. A switch housing 42 carries a contact 43 connected to one of the lead wires 29 by a wire 20a, and also carries a spring loaded contact 44 connected to the other of the lead wires 20 by a wire 20b. When the projectile is in the mortar, it bears against spring 41 moving the plunger outwardly to hold contact 44 out of engagement with contact 33. The spring load on contact 44 being greater than that exerted by spring 41 on plunger 40, when the projectile leaves the mortar the plunger is permitted to move inwardly, allowing the contacts to engage and close the switch.

Occasionally it becomes desirable, in geophysical exploration work, to simultaneously explode two distancespaced charges, as described in my co-pending application Serial No. 294,362, filed June 19, 1952. It will be apparent that my present invention may be utilized for suchpurpose, it only being necessary to substitute a projectile such as shown in my said co'pending application, for the projectile P. When two distance-spaced charges are thus exploded in" the air in such relationship that the shock wave of the highest explosion will reach the ground one wave-length behind the shock wave of the first explosive, the two waves will reinforce each other at the particular frequency corresponding to that wavelength, with the result that that frequency will be greatly accentuated; while th'e other frequencies in the spectrum will be diminished in intensity due to their random phase relationship;

In Figs. S--8, I show a modified arrangement not only for winding the projectile'firing cable carrying the leads but also for maintaining the cable in coiled condition until the projectile ispropelled upwardly from the ground.

Here I provide a pair of superimposed rotatable disks 50, 51, which, when assembled together, form a winding spool. Lower disk 50 is rotatably secured to a base 52 as' by a screw 53.

Adhesively or otherwise suitably secured to the top surface of the lower disk andpreferably arranged in a cross, I provide adhesive strips 54 the top surface 54a of each of which is coated preferably with a pressure sensitive or'permanently tacky adhesive capable of retaining the cable inspirally coiled condition against acci-' dental unwinding when not in use, but which will release the cable as the projectile moves upwardly from the ground without offering undue resistance to travel of the projectile. Of course the adhesive could be applied merely by coating the lower disk, but I find that'by using strips, as above described, it is easier to obtain the idealamount of adhesion of the cable to the disk.

The lower disk 50 has a round central spacer boss which is of the thickness of the cable or slightly less so that, as the cable is wound into an Archimedes spiral 'coil about the boss, adhesion of the cable to the stripswill be assured. The adhesive strips 54' terminate at the periphery of the boss.

The upper disk 51' is 'merely for retaining the cable in proper winding condition during the winding and has holes 60to pass screws 61' by which it is secured to the boss of the lower disk so that it will not rotate relative to the lower disk. The upper disk also has a center hole 63 to provide access to the screw 53 and has a hole 65 radially offset from hole63 to pass one end' of the cable as shown in Fig; 7.

Secured to the top of the disk 51, as by welding, in register with hole 65, there is a tubular guard member 66. In use, it is preferableto insert the firing cap 15, which is attached to one end of the cable, through hole 65and into the guard. This not only protects the firing cap during the winding but also holds that end of the cable against slipping around the boss during the start of the winding.

In use, the user places the firing cap 15 through hole 65 and into the guardmember, while the disks are separated, and lays the cable on the lower disk so that it may be wound about the boss 56. Then the upper disk is secured to the lower disk and, using the guard member as a handle, the user rotates the disks causing the cable to become wound in a spiral about the boss and to become lightly adheredto the strips 54. When it is ready to propel the projectile upwardly for firing, the upper disk is removed and the firing cap 15 inserted in the top end of the projectile in the mortar. Thusthe spiral coil may not accidentally become disturbed, and when the projectile is propelled from the mortar the coil will be gradually unwound from the inside of the coil. Of course, if preferred, the winding operation may be commenced by placing the opposite end of the cable in guard 66, in

which case the coil would be unwound from the outside ofthe coil as the projectile moves upwardly.

This arrangement overcomes difficulties in feeding out the cable While the projectile is moving upwardly.

I claim:

1. in a systern for creating an explosion at a predetermined height above the ground, the combination of a projectile carrying an explosive charge, a mortar adapted to receive said projectile, a propellant charge for propelling the projectile upwardly from the mortar, means for firing said propellant charge, an electrical circuit, a detonator. exposed to said explosive charge in the projectile, a switch controlling said circuit, said'switch'having I actuating means located at the ground, flexible electrical conductors connecting said detonator into said circuit,

said conductors being of a length equal to the height,

above the ground'at which said explosive charge is to be exploded andbeingphysically connected at their bottom ends tosaid switch actuating means, a second switch controlling saidconductors, means operable by said projectile'when the latter is'in said mortar to hold said second switch open, and means operative to automatically close said switch'when the projectile is discharged from said mortar.

2. In a system for firing an explosive projectile at a prtede'te'rminedheight above the ground, propelling means I for propelling the projectile upwardly from the ground,

an electrical circuit, a switch at the ground controlling said circuit, a disk located between said propelling means and said switch, said disk having an adhesive upon its upper surface, and a flexible cable conductively connecting said projectile into said circuit and physically connecting said-projectile to said switch, said cable being'arranged in a spiral c'oil bound to said diskby an adhesive member capable of releasing said cable in response to movement of'saidjprojectile upwardly fromsaid propelling means;

3'. The systemofclaim 2 wherein saidclisk is mounted for rotation.

4'. The systemof" claim 2' wherein said adhesive member comprises cir'c'mn'iferentially spaced radially arranged adhesively" coated strips.

5. In a system for firing anexplosive projectile connectedinto'an electricalcircuit by anelectrically conductive cable, means for forming the cable into a spiral coil and releasably retaining it in said position, comprising a base, a spoolcomposed of a lower disk having a top central bos's, an adhesive on the top surface of the lower disk outwardly from saidboss, an upper disk releasablysecured tosaidb'oss, and means rotatably securing said lower disk tosaidbase.

6. The systemof claim 5 wherein said adhesive is permanently tacky and isarranged on saidsurface in circumferentiall'y spaced radial lines.

ReferencesCitedin the file of this patent UNITED STATES PATENTS 203 ,274" Hunt May 7, 1878 372,958 Bradley et al. Nov. 8, 1887 932,270 Goodwin Aug. 24, 1909 1 ,235,637 Barlow Aug. 7,.1917 1,302,904 Duffie May 6, 1919 1,317,608 Barlow Sept. 30, 1919 1,349,014 Steinmetz Aug. 10, 1920 1,363,578 Edwards Dec. 28, 1920 2,399,136 Mount Apr. 23, 1946 2,490,378 Mount Dec. 6, 1949 FOREIGN PATENTS 10,057 Great Britain 1912 1,232. Netherlands Mar. 22, 1916 

